1. Technical Field of the Invention
The invention relates to techniques for scrambling bits of digital video signals and for descrambling the bits in a remote computer if certain conditions are met.
2. Background Art
With the advent of digital media and the increasingly widespread use of the Internet, cable, and satellite transmissions, the amount of video content creation is dramatically increasing. Content may be created for commercial purposes such as entertainment and advertising, or for more personal interests such as home videos and information for the hobbyist.
The term “streaming video” is often used to refer to point to point transmission of video, as opposed to broadcast video, wherein one computer sends the same signal to more than one receiving computer. Streaming video is often transmitted in real time. The term “video on demand” refers to the ability to request specific video content among various choices and have it provided as in streaming video.
For many content providers, there is a concern that sensitive or economically valuable content be provided to only specific individuals. Passwords and encryption have been used in an attempt to assure this. For example, an Internet provider may require a password before content is sent and/or the Internet provider may encrypt the content and expect the receiver to decrypt the content.
There are various formats for digital video. Common formats for digital video include MPEG (Moving Picture Experts Group) formats. Current and proposed MPEG formats include MPEG-1 (“Coding of Moving Pictures and Associated Audio for Digital Storage Media at up to about 1.5 MBits/s,” International Standard IS-11172, completed in 10.92), MPEG-2 (“Generic Coding of Moving Pictures and Associated Audio” Committee Draft CD 13818 as found in documents MPEG93/N601, N602, N603 (11.93)); and MPEG-4 (“Very Low Bitrate Audio-Visual Coding” Status: call for Proposals 11.94, Working Draft in 11.96). There are different versions of MPEG-1 and MPEG-2.